1. Field of the Invention
This invention relates in general to electrically actuated valves and more specifically to electrically actuated expansion valves for refrigeration systems.
2. Description of the Prior Art
Several types of electrically actuated valves suitable for use as expansion valves in refrigeration or air conditioning systems are known in the prior art. One type includes a solenoid connected to an appropriate electrical supply which, in response to a pulsed electrical signal, actuates a plunger or control element alternately into and out of a flow path through the expansion valve body to permit or prevent fluid flow. Another type of electrically actuated expansion valve has a rotary actuator with a means for converting the rotary motion into linear motion for operating a valve element to increase or decrease the flow area available through the valve body by seating against the valve seat to close the valve and prevent flow, or, moving linearly away from the valve seat, to permit flow through an area defined by the area of the opening between the valve element and the valve seat.
Representative U.S. patents which disclose solenoid actuated valves of this type include: U.S. Pat. No. 4,632,358 entitled Automotive Air Conditioning System Including Electrically Operated Expansion Valve; U.S. Pat. No. 4,807,445 entitled Refrigeration System, and, U.S. Pat. No. 4,840,039 entitled Automated Expansion Valve For a Refrigeration Circuit.
U.S. Pat. No. 4,986,085 entitled Incremental Electrically Actuated Valve discloses a refrigerant expansion valve of the type linearly actuated by a rotary stepper motor.